Heterolytic H₂ Activation Mediated by Low-Coordinate L₃Fe-(μ-N)-FeL₃ Complexes to Generate Fe(μ-NH)(μ-H)Fe Species

The diiron μ-nitride complexes, {L3FeII(μ-N)FeIIL3}- and L3FeIII(μ-N)FeIIL3, heterolytically activate hydrogen (1 atm) at ambient temperature in solution (L3 = [PhB(CH2PPh2)3]-). These transformations lead to structurally unique {L3FeII(μ-NH)(μ-H)FeIIL3}- and L3FeIII(μ-NH)(μ-H)FeIIL3 products. X-ray data establish a marked reduction in the Fe−Fe distance upon H2 uptake, and spectroscopic data establish both FeIIFeII species to be diamagnetic, whereas the FeIIIFeII species, L3FeIII(μ-N)FeIIL3 and L3FeIII(μ-NH)(μ-H)FeIIL3, populate doublet ground states with thermally accessible higher spin states.